Automotive electrical and electronic systems

ker88839_fm.qxd 1/9/06 11:37 AM Page i Automotive Electrical and Electronic Systems Classroom Manual Fifth Edition Update Chek-Chart John F Kershaw, Ed.D Revision Author James D Halderman Series Advisor Upper Saddle River, New Jersey Columbus, Ohio ker88839_fm.qxd 1/31/06 5:03 PM Page ii Executive Editor: Tim Peyton Editorial Assistant: Nancy Kesterson Production Editor: Christine Buckendahl Production Supervision: Angela Kearney, Carlisle Editorial Services Design Coordinator: Diane Y Ernsberger Cover Designer: Jeff Vanik Cover photo: Super Stock Production Manager: Deidra Schwartz Marketing Manager: Ben Leonard This book was set in Times by Carlisle Publishing Services It was printed and bound by Bind Rite Graphics The cover was printed by Lehigh Portion of materials contained herein have been reprinted with permission of General Motors Corporation, Service and Parts Operations License Agreement #0310805 Copyright © 2007 by Pearson Education, Inc., Upper Saddle River, New Jersey 07458 Pearson Prentice Hall All rights reserved Printed in the United States of America This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise For information regarding permission(s), write to: Rights and Permissions Department Pearson Prentice Hall™ is a trademark of Pearson Education, Inc Pearson® is a registered trademark of Pearson plc Prentice Hall® is a registered trademark of Pearson Education, Inc Pearson Education Ltd Pearson Education Singapore Pte Ltd Pearson Education Canada, Ltd Pearson Education—Japan Pearson Education Australia Pty Limited Pearson Education North Asia Ltd Pearson Educación de Mexico, S.A de C.V Pearson Education Malaysia Pte Ltd 10 ISBN 0-13-238883-9 ker88839_fm.qxd 1/9/06 11:37 AM Page iii Introduction Automotive Electrical and Electronic Systems is part of the Chek-Chart Series in Automotive Technology, which also includes: • Automatic Transmissions and Transaxles • Automotive Brake Systems • Automotive Heating, Ventilation, and Air Conditioning • Automotive Manual Drive Train and Rear Axle • Automotive Steering, Suspension, and Wheel Alignment • Automotive Engine Repair and Rebuilding • Engine Performance, Diagnosis, and Tune-Up • Fuel Systems and Emission Controls Since 1929, the Chek-Chart Series in Automotive Technology has provided vehicle specification, training, and repair information to the professional automotive service field Each book in the Chek-Chart series aims to help instructors teach students to become competent and knowledgeable professional automotive technicians The texts are the core of a learning system that leads a student from basic theories to actual hands-on experience The entire series is job-oriented, designed for students who intend to work in the automotive service profession Knowledge gained from these books and the instructors enables students to get and keep jobs in the automotive repair industry Learning the material and techniques in these volumes is a giant leap toward a satisfying, rewarding career NEW TO THE FIFTH EDITION UPDATE The fifth edition of Automotive Electrical and Electronic Systems has been updated to include new coverage of ignition systems Ignition coverage had been a standard feature of the text through the fourth edition, but was removed from the fifth edition Based on feedback from numerous users who wanted the ignition material back in the book, this updated fifth edition was produced It includes new ignition chapters in both the Classroom and Shop Manuals iii ker88839_fm.qxd 1/9/06 11:37 AM Page iv How to Use This Book WHY ARE THERE TWO MANUALS? Unless you are familiar with the other books in this series, Automotive Electrical and Electronic Systems is unlike any other textbook you have used before It is actually two books, the Classroom Manual and the Shop Manual They have different purposes and should be used together The Classroom Manual teaches what a technician needs to know about electrical and electronic theory, systems, and components The Classroom Manual is valuable in class and at home, both for study and for reference The text and illustrations can be used for years hence to refresh your memory about the basics of automotive electrical and electronic systems and also about related topics in automotive history, physics, mathematics, and technology This fifth edition update text is based upon detailed learning objectives, which are listed in the beginning of each chapter The Shop Manual teaches test procedures, troubleshooting techniques, and how to repair the systems and components introduced in the Classroom Manual The Shop Manual provides the practical, hands-on information required for working on automotive electrical and electronic systems Use the two manuals together to understand fully how the systems work and how to make repairs when something is not working This fifth edition update text is based upon the 2002 NATEF (National Automotive Technicians Education Foundation) Tasks, which are listed in the beginning of each chapter The fifth edition update Shop Manual contains Job Sheet assessments that cover the 56 tasks in the NATEF 2002 A6 Electrical/Electronics repair area WHAT IS IN THESE MANUALS? The following key features of the Classroom Manual make it easier to learn and remember the material: • Each chapter is based on detailed learning objectives, which are listed in the beginning of each chapter iv • Each chapter is divided into self-contained sections for easier understanding and review This organization clearly shows which parts make up which systems and how various parts or systems that perform the same task differ or are the same • Most parts and processes are fully illustrated with drawings or photographs Important topics appear in several different ways, to make sure other aspects of them are seen • A list of Key Terms begins each chapter These terms are printed in boldface type in the text and defined in the Glossary at the end of the manual Use these words to build the vocabulary needed to understand the text • Review Questions are included for each chapter Use them to test your knowledge • Every chapter has a brief summary at the end to help you review for exams • Brief but informative sidebars augment the technical information and present “real world” aspects of the subject matter The Shop Manual has detailed instructions on test, service, and overhaul procedures for modern electrical and electronic systems and their components These are easy to understand and often include stepby-step explanations of the procedure The Shop Manual contains: • ASE/NATEF tasks, which are listed in the beginning of each chapter and form the framework for the chapter’s content • A list of Key Terms at the beginning of each chapter (These terms are printed in boldface type where first used in the text.) • Helpful information on the use and maintenance of shop tools and test equipment • Safety precautions • Clear illustrations and diagrams to help you locate trouble spots while learning to read service literature • Test procedures and troubleshooting hints that help you work better and faster • Repair tips used by professionals, presented clearly and accurately • A sample test at the back of the manual that is similar to those given for Automotive Service ker88839_fm.qxd 1/9/06 11:37 AM Page v How to Use This Book Excellence (ASE) certification (Use this test to help you study and prepare when you are ready to be certified as an electrical and electronics expert.) WHERE SHOULD I BEGIN? If you already know something about automotive electrical and electronic systems and how to repair them, this book is a helpful review If you are just starting in automotive repair, then this book provides a solid foundation on which to develop professional-level skills Your instructor has designed a course that builds on what you already know and effectively uses the available facilities and equipment You may be asked to read certain chapters of these manuals out of order That’s fine The important thing is to really understand each subject before moving on to the next Study the Key Terms in boldface type and use the review questions to help understand the material v When reading the Classroom Manual, be sure to refer to the Shop Manual to relate the descriptive text to the service procedures When working on actual vehicle systems and components, look to the Classroom Manual to keep the basic information fresh in your mind Working on such a complicated piece of equipment as a modern automobile is not easy Use the information in the Classroom Manual, the procedures in the Shop Manual, and the knowledge of your instructor to guide you The Shop Manual is a good book for work, not just a good workbook Keep it on hand while actually working on a vehicle It will lie flat on the workbench and under the chassis, and it is designed to withstand quite a bit of rough handling When you perform actual test and repair procedures, you need a complete and accurate source of manufacturer specifications and procedures for the specific vehicle As the source for these specifications, most automotive repair shops have the annual service information (on paper, CD, or Internet formats) from the vehicle manufacturer or an independent guide v ker88839_fm.qxd 1/9/06 11:37 AM Page vi ker88839_fm.qxd 1/31/06 5:03 PM Page vii Acknowledgments The publisher sincerely thanks the following vehicle manufacturers, industry suppliers, and organizations for supplying information and illustrations used in the Chek-Chart Series in Automotive Technology Allen Testproducts American Isuzu Motors, Inc Automotive Electronic Services Bear Manufacturing Company Borg-Warner Corporation DaimlerChrysler Corporation Delphi Corporation Fluke Corporation Fram Corporation General Motors Corporation Honda Motor Company, Ltd Jaguar Cars, Inc Marquette Manufacturing Company Mazda Motor Corporation Mercedes-Benz USA, Inc Mitsubishi Motor Sales of America, Inc Nissan North America, Inc The Prestolite Company Robert Bosch Corporation Saab Cars USA, Inc Snap-on Tools Corporation Toyota Motor Sales, U.S.A., Inc Vetronix Corporation Volkswagen of America Volvo Cars of North America The comments, suggestions, and assistance of the following reviewers were invaluable: Rick Escalambre, Skyline College, San Bruno, CA, and Eugene Wilson, Mesa Community College, Mesa, AZ The publisher also thanks Series Advisor James D Halderman vii ker88839_fm.qxd 1/9/06 11:37 AM Page viii ker88839_fm.qxd 1/9/06 11:37 AM Page ix Contents Chapter — Tools, Fasteners, and Safety Learning Objectives Key Terms Threaded Fasteners Metric Bolts Grades of Bolts Nuts Washers Basic Tool List Tool Sets and Accessories 10 Brand Name Versus Proper Term 10 Safety Tips for Using Hand Tools 11 Measuring Tools 11 Safety Tips for Technicians 13 Safety in Lifting (Hoisting) a Vehicle 15 Electrical Cord Safety 17 Fire Extinguishers 19 Summary 20 Review Questions 20 Chapter — Introduction to Electricity Learning Objectives 21 Key Terms 21 What is Electricity? 22 Atomic Structure 22 Sources of Electricity 25 Historical Figures in Electricity 30 Summary 31 Review Questions 32 Chapter — Electrical Fundamentals Learning Objectives 35 Key Terms 35 Conductors and Insulators 36 Characteristics of Electricity 36 Complete Electrical Circuit 40 Ohm’s Law 42 Power 44 Capacitance 45 Summary 49 Review Questions 50 21 35 Chapter — Magnetism 53 Learning Objectives 53 Key Terms 53 Magnetism 54 Electromagnetism 55 Electromagnetic Induction 60 Transformers 65 Electromagnetic Interference (EMI) Suppression 65 Summary 68 Review Questions 70 Chapter — Series, Parallel, and SeriesParallel Circuits 71 Learning Objectives 71 Key Terms 71 Basic Circuits 71 Series Circuit 72 Parallel Circuit 72 Series Circuit Voltage Drops 73 Parallel Circuit Voltage Drops 75 Calculating Series Circuit Total Resistance 76 Calculating Parallel Circuit Total Resistance 78 Series-Parallel Circuits 79 Series and Parallel Circuit Faults 82 Summary of Series Circuit Operation 84 Summary of Parallel Circuit Operation 84 Review Questions 85 Chapter — Electrical Diagrams and Wiring 89 Learning Objectives 89 Key Terms 89 Wiring and Harnesses 90 Wire Types and Materials 92 Wire Size 93 Connectors and Terminals 96 Ground Paths 99 Multiplex Circuits 100 ix ker88839_fm.qxd 1/9/06 11:37 AM Page x x Contents Electrical System Polarity 103 Common Electrical Parts 103 Wire Color Coding 109 The Language of Electrical Diagrams 111 Diagrams 112 Summary 124 Review Questions 126 Chapter — Automotive Battery Operation 129 Learning Objectives 129 Key Terms 129 Electrochemical Action 130 Battery Electrolyte 134 State-of-Charge Indicators 135 Wet-Charged and Dry-Charged Batteries 136 Battery Charging Voltage 136 Battery Selection and Rating Methods 136 Battery Installations 138 Battery Installation Components 140 Battery Life and Performance Factors 142 Summary 144 Review Questions 145 Chapter — Charging System Operation 147 Learning Objectives 147 Key Terms 147 Charging System Development 148 DC Generator 148 Charging Voltage 148 Diode Rectification 150 AC Generator (Alternator) Components 152 Current Production in an AC Generator 156 Voltage Regulation 161 Electromagnetic Regulators 162 Solid-state Regulators 163 Charge/Voltage/Current Indicators 168 Charging System Protection 170 Complete AC Generator Operation 170 AC Generator (Alternator) Design Differences 171 Summary 179 Review Questions 181 Chapter — Starting System Operation 183 Learning Objectives 183 Key Terms 183 Starting System Circuits 184 Basic Starting System Parts 184 Specific Starting Systems 188 Starter Motors 192 Frame and Field Assembly 192 DC Starter Motor Operation 194 Armature and Commutator Assembly 197 Permanent-Magnet Fields 197 Starter Motor and Drive Types 198 Overrunning Clutch 203 Summary 204 Review Questions 206 Chapter 10 — Automotive Electronics 209 Learning Objectives 209 Key Terms 209 Semiconductors 210 Electrostatic Discharge (ESD) 213 Diodes 213 Photonic Semiconductors 215 Rectifier Circuits 216 Transistors 217 Silicon-Controlled Rectifiers (SCRs) 221 Integrated Circuits 222 Using Electronic Signals 222 Summary 223 Review Questions 224 Chapter 11 — The Ignition Primary and Secondary Circuits and Components 227 Learning Objectives 227 Key Terms 227 Need for High Voltage 228 High Voltage Through Induction 228 Basic Circuits and Current 229 Primary Circuit Components 230 Switching and Triggering 230 Monitoring Ignition Primary Circuit Voltages 234 Primary and Secondary Circuits 236 Ignition Coils 237 Distributor Cap and Rotor 247 Ignition Cables 250 Spark Plugs 250 Spark Plug Construction 252 Summary 255 Review Questions 256 Chapter 12 — Automotive Lighting Systems 257 Learning Objectives 257 Key Terms 257 Headlamp Circuits 258 Common Automotive Bulbs 268 Taillamp, License Plate Lamp, and Parking Lamp Circuits 269 Stop Lamp and Turn Signal Circuits 270 Hazard Warning Lamp (Emergency Flasher) Circuits 274 Backup Lamp Circuits 275 Side Marker and Clearance Lamp Circuits 276 ker88839_ch15.qxd 1/9/06 11:36 AM Page 340 340 Chapter Fifteen Figure 15-38 2002 GM Cadillac Seville keyless entry system schematic (GM Service and Parts Operations) Unlock All Doors—Second Operation Rear Compartment Lid Release Momentarily press the UNLOCK button a second time, within four seconds of the first press, in order to perform the following functions: If the vehicle transaxle is in Park or Neutral and the ignition is in the OFF position, a single press of the rear compartment release button will open the rear compartment lid The interior lamps will not illuminate • Unlock the remaining doors • Illuminate the interior lamps for approxi- mately 40 seconds or until the ignition is turned ON • Flash the exterior lights, if selected ON in personalization • Chirp the horn, if selected ON in personalization Fuel Door Release If the vehicle transaxle is in PARK or NEUTRAL and the ignition is in the OFF position, a single press of the fuel-door release button will open the fuel door Lock All Doors Keyless Entry Personalization Press the LOCK button in order to perform the following functions: The exterior lamps and horn chirp may be personalized for two separate drivers as part of the remote activation verification feature • Lock all of the doors and immediately turn off the interior lamps • Flash the exterior lights, if selected ON in personalization • Chirp the horn, if selected ON in personalization • Arm the content theft deterrent (CTD) system Rolling Code The keyless entry system uses rolling code technology Rolling code technology prevents anyone from recording the message sent from the transmitter and using the message in order to gain entry to the vehicle The term rolling code refers ker88839_ch15.qxd 1/9/06 11:36 AM Page 341 Body Accessory Systems Operation to the way that the keyless entry system sends and receives the signals The transmitter sends the signal in a different order each time The transmitter and the remote control door lock receiver (RCDLR) are synchronized to the appropriate order If a programmed transmitter is out of synchronization, it sends a signal that is not in the order that the RCDLR expects This will occur after 256 presses of any transmitter button that is out of range of the vehicle Automatic Synchronization The keyless entry transmitters not require a manual synchronization procedure If needed, the transmitters automatically resynchronize when any button on the transmitter is pressed within range of the vehicle The transmitter will operate normally after the automatic synchronization DaimlerChrysler Keyless Entry Systems The DaimlerChrysler keyless entry system also uses a key fob-style radio transmitter, (Figure 15-39) to unlock and lock the vehicle doors and deck lid This multipurpose system is similar to many aftermarket theft-deterrent systems, since it turns on the interior lamps, disarms the factory-installed antitheft system, and chirps the horn whenever it is used The transmitter attaches to the key ring and has three buttons for operation within 23 feet (7 meters) of the vehicle module receiver The transmitter has its own code stored in the module memory If the transmitter is lost or stolen, or an 341 additional one is required, a new code must be stored in module memory Figure 15-40 shows the integration of the keyless entry, illuminated entry, vehicle theft security, and power door lock systems with the BCM THEFT DETERRENT SYSTEMS Antitheft systems are usually aftermarket installations, although in recent years, some manufacturers have offered factory-installed systems on the luxury vehicles in their model line Basic antitheft systems provide a warning when a forced entry is attempted through the car doors or the trunk lid A starter interlock feature is incorporated on some models System functioning relies on strategically located switches installed in the door jambs, the door lock cylinders, and the trunk lock cylinder (Figure 15-41) After the system is armed, any tampering with the lock cylinders or an attempt to open any door or the trunk lid without a key causes the alarm controller to trigger the system Once a driver has closed the doors and armed the system, an indicator lamp in the instrument cluster comes on for several seconds, and then goes out The system is disarmed by unlocking a front door from the outside with the key or turning the ignition on within a specified time If the alarm has been set off, the system can be disarmed by unlocking a front door with the key Delphi (Delco) UTD System Figure 15-39 DaimlerChrysler keyless entry system key fob-style radio transmitter (DaimlerChrysler Corporation) The Delphi universal theft deterrent (UTD) system was introduced on some 1980 GM models and offered as an option until it was superseded by the personal automotive security system (PASS) The circuitry, logic, and power relays that operate the system are contained within a controller module When the system is armed by the driver, a security system warning lamp in the instrument panel glows for four to eight seconds after the doors have been closed, then shuts off The system can be disarmed without sounding the alarm by unlocking a front door from the outside with a key, or by turning the ignition switch on If the alarm has sounded, it can be shut off by unlocking one of the front doors with a key ker88839_ch15.qxd 1/9/06 11:36 AM Page 342 342 Chapter Fifteen Figure 15-40 DaimlerChrysler keyless entry system schematic (DaimlerChrysler Corporation) If the system is armed and a door is opened forcibly, a two-terminal doorjamb switch activates the alarm through one terminal The other switch terminal operates the interior lights On vehicles with power door locks, the circuits are separated by a diode Tamper switches are installed in all door locks and the trunk lid lock (Figure 15-42) The switches are activated by any rotation or in-and-out movement of the lock cylinders during a forced entry A disarm switch in the LH door cylinder (Figure 15-43) allows the owner to deactivate the system without sounding the alarm before entering the vehicle All tamper switches should be kept clean, as corrosion can cause the system to activate without apparent reason Exact wiring of the UTD system depends on the particular vehicle and how it is equipped To understand just how the system works on a given vehicle, you must have the proper wiring diagram ker88839_ch15.qxd 1/9/06 11:36 AM Page 343 Body Accessory Systems Operation Figure 15-41 System functioning relies on strategically located switches installed in the door jambs, the door lock cylinders, and the trunk lock cylinder (GM Service and Parts Operations) 343 Figure 15-43 The UTD disarm switch is part of the LH door lock cylinder (GM Service and Parts Operations) Figure 15-44 Delphi (Delco) VATS system (GM Service and Parts Operations) • Starter enable relay • PCM • Wiring harness Figure 15-42 Tamper switches are installed in all door locks and the trunk lid lock (GM Service and Parts Operations) Delphi (Delco) VATS/PASS-Key II™ System The Delco (Delphi) vehicle antitheft system (VATS), introduced as standard equipment on the 1986 Corvette (Figure 15-44) functions as an ignition-disable system It is not designed to prevent a forced entry, but to protect the steering column lock if an intruder breaks into the vehicle When used on Corvettes with the UTD system, the combination is called the forced entry alarm system (FES) When used on other GM vehicles, VATS is called PASS-Key II™ The system (Figure 15-45) consists of the following components: • Resistor ignition key • Steering column lock cylinder with resistor- sensing contact • VATS or PASS-Key II™ decoder module A small resistor pellet embedded in the ignition key contains one of 15 different resistance values The key is coded with a number that indicates which resistor pellet it contains Resistor pellet resistance values vary according to key code and model year To operate the lock, the key must have the proper mechanical code (1 of 2,000); to close the starter circuit, it must also have the correct electrical code (1 of 15) Inserting the key in the ignition lock cylinder brings the resistor pellet in contact with the resistor sensing contact Rotating the lock applies battery power to the decoder module (Figure 15-45) The sensing contact sends the resistance value of the key pellet to the decoder module, where it is compared to a fixed resistance value stored in memory If the resistor code and the fixed value are the same, the decoder module energizes the starter enable relay, which closes the circuit to the starter solenoid and allows the engine to crank At the same time, the module sends a pulse-width modulated (PWM) cranking fuel-enable signal to the PCM ker88839_ch15.qxd 1/9/06 11:36 AM Page 344 344 Chapter Fifteen Figure 15-45 PASS-Key circuit diagram (GM Service and Parts Operations) If the key resistor code and the module’s fixed resistance value not match, the module shuts down for two to four minutes Repeating the attempt to start the vehicle with the wrong key will result in continued module shutdowns During vehicle operation, the key resistor pellet inputs are continually read If the module sees an open, short, or incorrect resistance value for 60 consecutive seconds, a Security indicator lamp comes on and remains lighted until the fault is corrected The lamp also comes on for five seconds when the ignition is first turned on This serves as a bulb check and indicates that the system is functioning properly DaimlerChrysler Antitheft Security System This passive-arming theft-deterrent system (Figure 15-46) is factory installed on high-line Chrysler models and functions like many aftermarket alarm installations When combined with the Remote Keyless Entry (Figure 15-40), the system becomes an active arming system Once armed, the doors, hood, and trunk lid all are monitored for unauthorized entry The system is passively armed by activating the power door locks before closing the driver’s door; it will not arm if the doors are locked manually The system is actively armed if the doors are locked with the RKE transmitter A SET lamp in the instrument cluster flashes for 15 seconds during the arming period If a forcible entry is attempted while the system is armed, it responds by sounding the horn, flashing the park and taillamps, and activating an engine kill feature The system is passively disarmed by unlocking either front door with the key, or actively disarmed by using the RKE transmitter If the alarm has been activated during the driver’s absence, the horn will blow three times when the vehicle is disarmed as a way of informing the driver of an attempted entry or tampering Ford Antitheft System This antitheft system bears many similarities to the Delco UTD theft-deterrent system It is installed on luxury models, uses many of the ker88839_ch15.qxd 1/9/06 11:36 AM Page 345 Body Accessory Systems Operation 345 Figure 15-46 DaimlerChrysler antitheft security system (DaimlerChrysler Corporation) same components, and functions in essentially the same way Once the system is armed, any tampering with the doors, hood, or trunk lid signals the control module Once triggered, the system flashes the low-beam headlamps, the parking lamps, and alarm indicator lamp on and off; sounds the horn; and interrupts the starter circuit The system is composed of the following components: • • • • • • Antitheft control module Antitheft warning indicator Door-key unlock switches Hood switch Trunk-lid lock-cylinder tamper switch Ignition-key lock-cylinder sensor It also incorporates the following components from other systems: • • • • • • • Power door lock switches Door-ajar switches Horn relay Low-beam headlamps Parking lamps Keyless entry module Starter relay CRUISE CONTROL SYSTEMS The cruise control system is one of the most popular electronic accessories installed on today’s vehicles During open-road driving it can maintain a constant vehicle speed without the continued effort of driver This helps reduce driver fatigue and increases fuel economy Several override features built into the cruise control system allow the vehicle to be accelerated, slowed, or stopped Problems with the system can vary from no operation, to intermittent operation, to not disengaging To diagnose these system complaints, today’s technicians must rely on their knowledge and ability to perform an accurate diagnosis Most of the system is tested using familiar diagnostic procedures; build on this knowledge and ability to diagnose cruise control problems Use system schematics, troubleshooting diagnostics, and switch continuity charts to assist in isolating the cause of the fault Most vehicle manufacturers have incorporated self-diagnostics into their cruise control systems This allows some means of retrieving trouble codes to assist the technician in locating system faults ker88839_ch15.qxd 1/9/06 11:36 AM Page 346 346 Chapter Fifteen On any vehicle, perform a visual inspection of the system Check the vacuum hoses for disconnects, pinches, loose connections, etc Inspect all wiring for tight, clean connections Also, look for good insulation and proper wire routing Check the fuses for opens and replace as needed Check and adjust linkage cables or chains, if needed Some manufacturers require additional preliminary checks before entering diagnostics In addition, perform a road test (or simulated road test) in compliance with the service manual to confirm the complaint ter or sides of the steering wheel There are usually several functions on the switch, including off-on, resume, and engage buttons The switch is different for resume and non-resume systems The transducer is a device that controls the speed of the vehicle When the transducer is engaged, it senses vehicle speed and controls a vacuum source (usually the intake manifold) The vacuum source is used to maintain a certain position on a servo The speed control is sensed from the lower cable and casing assembly attached to the transmission CAUTION: When servicing the cruise control system, you will be working close to the air bag and antilock brake systems.The service manual will instruct you when to disarm and/or depressurize these systems Failure to follow these procedures can result in injury and additional costly repairs to the vehicle When engaged, the cruise control components set the throttle position to the desired speed The speed is maintained unless heavy loads and steep hills interfere The cruise control is disengaged whenever the brake pedal is depressed The common speed or cruise control system components function in the following manner Cruise Control Switch The cruise control switch (Figure 15-47) is located on the end of the turn signal lever or near the cen- Figure 15-47 Cruise control switch The servo unit is connected to the throttle by a rod or linkage, a bead chain, or a Bowden cable The servo unit maintains the desired car speed by receiving a controlled amount of vacuum from the transducer The variation in vacuum changes the position of the throttle When a vacuum is applied, the servo spring is compressed and the throttle is positioned correctly When the vacuum is released, the servo spring is relaxed and the system is not operating Two switches are activated by the position of the brake pedal When the pedal is depressed, the brake-release switch disengages the system ker88839_ch15.qxd 1/9/06 11:36 AM Page 347 Body Accessory Systems Operation 347 From fuse panel Speed control switch assembly On Resume Off Stop light switch From fuse panel From fuse panel Speed control amplifier Speed sensor Coast Set Accelerate Speed control servo Actuator Connects ot throttle linkage Figure 15-49 Cruise control system component circuit (GM Service and Parts Operations) Figure 15-48 Cruise control system schematic (GM Service and Parts Operations) A vacuum-release valve is also used to disengage the system when the brake pedal is depressed Electrical and Vacuum Circuits Figure 15-48 shows an electrical and vacuum circuit diagram The system operates by controlling vacuum to the servo through various solenoids and switches Electronic Cruise Control Components Cruise control can also be obtained by using electronic components rather than mechanical components Depending on the vehicle manufacturer, several additional components may be used The electronic control unit is used to control the servo unit The servo unit is again used to control the vacuum, which in turn controls the throttle The vehicle speed sensor (VSS) buffer amplifier is used to monitor or sense vehicle speed The signal created is sent to the electronic control module A generator speed sensor may also be used in conjunction with the VSS The clutch switch is used on vehicles with manual transmissions to disengage the cruise control when the clutch is depressed The accumulator is used as a vacuum storage tank on vehicles that have low vacuum during heavy load and high road speed Figure 15-49 shows how electronic cruise control components work together The servo unit controls the throttle position, using a vacuum working against spring pressure to operate an internal diaphragm The controller controls the servo unit vacuum circuit electronically The controller has several inputs that help determine how it will affect the servo, including a brake-release switch (clutch-release switch), a speedometer, a buffer amplifier (generator speed sensor), a turn signal lever mode switch, and speed-control switches on the steering wheel SUPPLEMENTAL RESTRAINT SYSTEMS A typical supplemental inflatable restraint (SIR) or air bag system (Figure 15-50) includes three important elements: the electrical system, air bag module, and knee diverter The electrical system includes the impact sensors and the electronic control module Its main functions are ker88839_ch15.qxd 1/9/06 11:36 AM Page 348 348 Figure Chapter Fifteen 15-50 SRS components (DaimlerChrysler Corporation) cuits and energizes the system readiness indicator during prove-out and whenever a fault occurs System electrical faults can be detected and translated into coded indicator displays If a certain fault occurs, the microcomputer disables the system by opening a thermal fuse built into the monitor If a system fault exists and the indicator is malfunctioning, an audible tone signals the need for service If certain faults occur, the system is disarmed by a firing circuit disarm device incorporated within the monitor or diagnostic module Trouble codes can be retrieved through the use of a scan tool or flash codes, and on some models through the digital panel cluster (if equipped) As CAUTION: When servicing the air bag system, the service manual will instruct you when and how to disarm the system Failure to follow these procedures can result in injury and additional costly repairs to the vehicle to conduct a system self-check to let the driver know that it is functioning properly, to detect an impact, and to send a signal that inflates the air bag The air bag module is located in the steering wheel for the driver and in the dash panel for passengers; it contains the air bag and the parts that cause it to inflate The knee diverter cushions the driver’s knee from impact and helps prevent the driver from sliding under the air bag during a collision It is located underneath the steering column and behind the steering column trim Electrical System Components The electrical system generally has the following parts: Diagnostic Monitor Assembly The diagnostic monitor contains a microcomputer that monitors the electrical system components and connections The monitor performs a self-check of the microcomputer internal cir- with all diagnostics, consult the appropriate service manual for the correct procedures An air-bag-system backup power supply is included in the diagnostic monitor to provide air bag deployment power if the battery or battery cables are damaged in an accident before the crash sensors close The power supply depletes its stored energy approximately one minute after the positive battery cable is disconnected Sensors The sensors detect impact (Figure 15-51) and signal the air bag to inflate At least two sensors must be activated for the air bag to inflate There are usually five sensors: two at the radiator support, one at the right-hand fender apron, one at the left-hand fender apron, and one at the cowl in the passenger compartment However, a few systems use only two sensors—one in front of the radiator and another in the passenger compartment There is an interlock between the sensors, so two or more must work together to trigger the system Keep in mind that air bag systems are designed to deploy in case of frontal collisions CAUTION: The backup power supply energy must be depleted before any air bag component service is performed To deplete the backup power supply energy, disconnect the positive battery cable and wait one minute ker88839_ch15.qxd 1/9/06 11:36 AM Page 349 Body Accessory Systems Operation 349 CAN BATTERY (+) GROUND (-) AIR BAGS SAFING SENSOR CRASH SENSORS O-RINGS SEALS Figure 15-52 Safing sensor (GM Service and Parts SENSING MASS ELECTRICAL CONTACTS Operations) BIAS MAGNET FRONT OF CAR MOUNTING PLATE Wiring Shield Steering Wheel Figure 15-51 SRS sensors (DaimlerChrysler Corporation) Retainer Ring only Although the design of individual systems varies, the vehicle must be traveling a minimum of 12–28 mph before the system is armed and ready for deployment All the sensors use some type of inertia switching mechanism that provides for the breakaway of a metal ball from its captive magnet This function causes a signal to activate a portion of the deployment program set up in the control processor The system is still capable of directly applying battery power to the squib or detonator At least two sensors, one safing sensor and one front crash sensor, must be activated to inflate the air bag Safing Sensors An integrated version of this network includes a safing sensor (Figure 15-52), sometimes attached to the original crash sensor This device confirms the attitude and magnitude of the frontal deceleration forces and offers the microprocessor a second opinion before actual deployment This is all it takes to complete the firing sequence, and the bag will deploy Wiring Harness The wiring harness connects all system components into a complete unit The wires carry the electricity that signals the air bag to inflate The harness also passes the signals during the selfdiagnosis sequence Inflater Igniter Mounting Assembly Plate Figure 15-53 Module Liner Trim Cover Assembly Bag Assembly Air bag module (DaimlerChrysler Corporation) SIR or Air Bag Readiness Light This light lets the driver know the air bag system is working and ready to its job The readiness lamp lights briefly when the driver turns the ignition key from OFF to RUN A malfunction in the air bag system causes the light to stay on continuously or to flash, or the light might not come on at all Some systems have a tone generator that sounds if there is a problem in the system or if the readiness light is not functioning Air Bag Module The bag itself is composed of nylon and is sometimes coated internally with neoprene All the air bag module (Figure 15-53) components are packaged in a single container, which is mounted in the center of the steering wheel or in the dash panel on the passenger side The entire assembly must be serviced as one unit when repair of the air bag system is required The air bag module is made up of the following components ker88839_ch15.qxd 1/9/06 11:36 AM Page 350 350 Chapter Fifteen Igniter and Housing Assembly Intensifier Assembly Steering Wheel Clock Spring Electrical Connector Generant Housing Air Bag Module Elastomeric Seal Steering Column Vibration Damper FWD Automatic Transmission Only Filter/Cooling Media Generant Figure 15-55 Liner and steering wheel trim cover (GM Service and Parts Operations) Figure 15-54 Igniter assembly (GM Service and Parts Operations) Igniter Assembly (Figure 15-55) Inflation of the air bag is caused by an explosive release of gas For the explosion to occur, a chemical reaction must be started The igniter assembly does this when it receives a signal from the air bag monitor Actually, the igniter is a two-pin bridge device: When the electrical current is applied, it arcs across the two pins, creating a spark that ignites a squib (canister of gas) that generates zirconic potassium perchlorate (ZPP) This material ignites the propellant Some newer model air bags now use solid propellant and argon This gas has a stable structure, cools more quickly, and is inert as well as non-toxic systems In addition, a certain degree of facial protection against flying objects is obtained just when it is needed It is important to remember that only the tandem action of at least one main sensor and a safing sensor initiates safety restraint system activation The micro-controller also provides failure data and trouble codes for use in servicing various aspects of most systems Mounting Plate and Retainer Ring The mounting plate and retainer ring attach the air bag assembly to the inflator They also keep the entire air bag module connected to the steering wheel Inflator Module The inflator module contains the ZPP Once it triggers the igniter, the propellant charge is progressive, burning sodium azide, which converts to nitrogen gas as it burns It is the nitrogen gas that fills the air bag Almost as soon as the bag is filled, the gas is cooled and vented, deflating the assembly as the collision energy is absorbed The driver is cradled in the envelope of the supplemental restraint bag instead of being propelled forward to strike the steering wheel or be otherwise injured by follow-up inertia energy from seat belt restraint Liner and Steering Wheel Trim Cover (Figure 15-56) The liner houses the air bag; the trim cover goes over the exterior of the steering wheel hub Passenger-side air bags are very similar in design to the driver’s unit The actual capacity of gas required to inflate the bag is much greater because the bag must span the extra distance between the occupant and the dashboard at the passenger seating location The steering wheel and column make up this difference on the driver’s side WARNING: When the air bag is deployed, a great deal of heat is generated Although the heat is not harmful to passengers, it may damage the clock spring electrical connector.When replacing a deployed air bag module, examine all of the electrical connections for signs of scorching or damage If damage exists, it must be repaired ker88839_ch15.qxd 1/9/06 11:36 AM Page 351 Body Accessory Systems Operation SUMMARY Heating and air-conditioning systems share a motor-driven fan The motor speeds usually are controlled by varying the resistance in the motor circuit Air-conditioning systems also have an electromagnetic clutch on the compressor The clutch is energized by the air-conditioning system control switch A clutch-cycling pressure switch turns the compressor clutch on and off as needed to maintain desired evaporator pressure and temperature Other switches are used in the clutch circuit to protect the system from high or low pressure, or to shut the clutch off under certain conditions, such as wide-open throttle Older vehicles may use a fan and motor as a rear-window defogger; this system is similar to the heating system A rear-window defroster or defogger on late-model vehicles is a grid of conductors attached to the rear window A relay usually controls current to the conductors Ford’s heated windshield system uses current directly from the alternator The parts of a sound system that concern most service technicians include the way the sound unit and the speakers are mounted, interference capacitors, panel illumination bulbs, and power antennas Power windows are moved by a reversible motor Motor direction is controlled by current through different brushes The driver’s-side master switch controls all of the windows, because each individual switch is grounded through the master switch Power seats can be moved by one, two, or three motors and various transmission units Permanentmagnet motors or electromagnetic field motors can be used Current to the motors sometimes is controlled by a relay Power door locks, trunk latches, and seat-back releases can be moved by solenoids or motors Relays are often used to control current to the solenoid or motor ADL systems are a safety feature integrated with the power door locks They automatically lock all doors before the vehicle is driven Keyless entry systems are both convenience and safety features: They allow a driver access to a vehicle by entering a code through a keypad on the driver’s door, or by depressing a button on a key chain transmitter Theft-deterrent systems such as the Delco UTD and Ford Antitheft System are factory installed on luxury cars Such systems use other vehicle systems to sound an alarm when the car is tampered with The Delco VATS/PASS-Key II™ 351 system uses a resistor ignition key that is “read” by the lock cylinder when inserted If the resistance and the memory value not match, the system shuts down the ignition and the starter When engaged, the cruise control components set the throttle position to the desired speed The speed is maintained unless heavy loads and steep hills interfere The cruise control is disengaged whenever the brake pedal is depressed The cruise control switch is located on the end of the turn signal lever or near the center or sides of the steering wheel There are usually several functions on the switch, including off-on, resume, and engage buttons The switch is different for resume and non-resume systems The transducer is a device that controls the speed of the vehicle When the transducer is engaged, it senses vehicle speed and controls a vacuum source (usually the intake manifold) The vacuum source is used to maintain a certain position on a servo The speed control is sensed from the lower cable and casing assembly attached to the transmission The servo unit is connected to the throttle by a rod or linkage, a bead chain, or a Bowden cable The servo unit maintains the desired car speed by receiving a controlled amount of vacuum from the transducer The variation in vacuum changes the position of the throttle When a vacuum is applied, the servo spring is compressed and the throttle is positioned correctly When the vacuum is released, the servo spring is relaxed and the system does not operate Two switches are activated by the position of the brake pedal When the pedal is depressed, the brake release switch disengages the system A vacuum release valve is also used to disengage the system when the brake pedal is depressed The Supplemental Inflatable Restraint (SIR) or air bag system includes three important elements The electrical system includes the impact sensors and the electronic control module Its main functions are to conduct a system self-check to let the driver know that it is functioning properly, to detect an impact, and to send a signal that inflates the air bag The air bag module is located in the steering wheel for the driver and in the dash panel for passengers It contains the air bag and the parts that cause it to inflate The knee diverter cushions the driver’s knee from impact and helps prevent the driver from sliding under the air bag during a collision It is located underneath the steering column and behind the steering column trim Newer vehicles contain SIR systems in the side panels and headliner or curtains ker88839_ch15.qxd 1/9/06 11:36 AM Page 352 352 Chapter Fifteen Review Questions Technician A says an electronic climate control (ECC) system with BCM control cycles the power to the compressor clutch Technician B says an electronic climate control (ECC) system without BCM control cycles the ground circuit to the compressor clutch Who is right? a A only b B only c Both A and B d Neither A nor B Technician A says Ford’s heated windshield system uses a conductive grid bonded to the outside surface of the glass Technician B says the conductive grid is applied to the back of the outer glass layer before it is laminated to the inner glass layer Who is right? a A only b B only c Both A and B d Neither A nor B Constant operation of the compressor in automotive air-conditioning systems is prevented by: a A solenoid b A servomagnet c An electromagnetic clutch d A one-way clutch Individual switches on automobile power window circuits must be connected in with the driver’s side master switch a Series b Shunt c Parallel d Series-parallel The air-conditioning compressor clutch can be controlled by: a A power steering cutout switch b A pressure cycling switch c Both A and B d Neither A nor B Technician A says the user selects the mode in a semiautomatic temperature control system, but the actuators are electrically operated Technician B says a semiautomatic temperature control system uses in-car and ambient temperature sensors Who is right? a b c d A only B only Both A and B Neither A nor B Technician A says the body control module (BCM) talks to other computers in an ECC system on a serial data line Technician B says the ECC system programmer activates the actuators on a serial data line Who is right? a A only b B only c Both A and B d Neither A nor B GM power seat system motors use: a Permanent-magnet fields b Electromagnetic fields c Both A and B d Neither A nor B The Delphi (Delco) vehicle antitheft system (VATS) uses a _ in the ignition key a Thermistor b Potentiometer c Magnet d Resistor 10 Power window systems use: a Unidirectional motors b Reversible motors c Stepper motors d Servomotors 11 Technician A says Ford’s heated windshield system will work only if the in-car temperature is above 40˚F (4˚C) Technician B says the heated windshield module can control the EEC-IV module under certain circumstances Who is right? a A only b B only c Both A and B d Neither A nor B 12 Technician A says a keyless entry system incorporates the function of an illuminated entry system Technician B says moving the gear selector into Drive with the ignition on activates an ADL system Who is right? a A only b B only ker88839_ch15.qxd 1/9/06 11:36 AM Page 353 Body Accessory Systems Operation c Both A and B d Neither A nor B 13 Technician A says the Delco Remote Keyless Entry (RKE) and the Remote Lock Control (RLC) are different keyless entry systems Technician B says the RKE and RLC systems are subsystems of the VAT and PASS systems Who is right? a A only b B only c Both A and B d Neither A nor B 14 Technician A says if the resistance value of the ignition key in the PASS system does not match the UHF value stored in the receiver’s memory, the vehicle will not start Technician B says a factory-installed theftdeterrent system is a complex multiplecircuit system Who is right? a A only b B only c Both A and B d Neither A nor B 15 In a cruise control system, which component controls the amount of vacuum that is applied to the servo unit? a The throttle body b The cruise control switch c The transducer d The brake pedal position switch 16 Which of the following actions will deactivate cruise control operation? a Applying the accelerator pedal b Applying the brake 353 c Driving up a steep hill d Releasing the accelerator pedal 17 In an electronically controlled cruise control system, what component is used to monitor vehicle speed? a Wheel speed sensor b Generator speed sensor c Turbine speed sensor d Vehicle speed sensor 18 What enables an air bag to deploy in an accident, even if the battery becomes disconnected during the crash? a A mechanical push-arm igniter b A backup power supply c The velocity versus solid object sensor d A “sudden stop” signal received from the vehicle speed sensor 19 Though different manufacturers have different specifications, how fast must a vehicle be moving before the air bag system is armed and ready to deploy if needed? a Any speed above zero b Between and 10 mph c Between 12 and 28 mph d At least 45 mph 20 When servicing an air bag, what is the first step you should take? a Disconnect the battery negative cable b Disconnect the clockspring electrical connector c Take resistance measurements at all electrical connectors d Disconnect the impact sensors ker88839_ch15.qxd 1/9/06 11:36 AM Page 354 ... Introduction Automotive Electrical and Electronic Systems is part of the Chek-Chart Series in Automotive Technology, which also includes: • Automatic Transmissions and Transaxles • Automotive Brake Systems. .. ready to be certified as an electrical and electronics expert.) WHERE SHOULD I BEGIN? If you already know something about automotive electrical and electronic systems and how to repair them, this... chapter reviews all of the basic electrical principles required to understand electronics and the automotive electrical/ electronic systems in the later chapters An automotive technician must have